FR3079991A1 - METHOD FOR TRANSMITTING A MONOCHROME DIGITAL IMAGE VIA A TRANSMISSION INTERFACE COMPRISING A PLURALITY OF TRANSMISSION CHANNELS - Google Patents

Abstract

The present invention relates to a method for transmitting (100) a monochrome digital image from a digital image source connected to a monochrome screen by means of a transmission interface comprising a plurality of transmission channels (CT1 , CT2, CT3), the monochrome image comprising a plurality of image pixels (PI), the monochrome screen comprising a plurality of display pixels (PA), the method (100) being characterized in that it involves the following steps: - (110) distributing the image pixels (PI) into a plurality of groups of pixels (GNb, G1 Nb ', G2Nb', G3Nb ', G4Nb'); - (120) successively transmit the groups of pixels from the source of digital images to the monochrome screen via the transmission interface, the image pixels (PI) of each group of pixels being transmitted in parallel via the channels of transmission (CT 1, CT2, CT3); - (130) assigning each image pixel (PI) received by the monochrome screen to a corresponding display pixel (PA) so as to reconstruct the digital image on the monochrome screen.   

Description

METHOD FOR TRANSMITTING A MONOCHROME DIGITAL IMAGE VIA A TRANSMISSION INTERFACE HAVING A PLURALITY OF TRANSMISSION CHANNELS

TECHNICAL FIELD OF THE INVENTION

The present invention relates to a method for transmitting a monochrome digital image via a transmission interface comprising a plurality of transmission channels.

TECHNOLOGICAL BACKGROUND OF THE INVENTION

A digital image is made up of a multitude of pixels arranged in the form of a matrix. Conventionally, each pixel is coded on three components which each correspond to a primary color, generally red, green and blue. We speak in this case of RGB coding (or "RGB" according to English terminology).

The digital image is transmitted from a digital image source to a screen using an interface with three transmission channels, each transmission channel being dedicated to one of the color components. The three color information of each pixel can thus be transmitted in parallel.

Once received by the screen, the digital color image can be transformed into a monochrome image. To do this, a light intensity level E’s is calculated there for each pixel from the three components R, G and B according to the following equation:

E'y = 0.299 X R + 0.587 X G + 0.114 X B

However, to date there is no method of directly transmitting a monochrome digital image from a digital image source directly to a monochrome screen. There is therefore a need for such a method.

SUMMARY OF THE INVENTION

The present invention aims to meet this need by proposing a method for transmitting a monochrome digital image originating from a source of digital images connected to a monochrome screen by means of a transmission interface comprising a plurality of transmission channels. , the monochrome image comprising a plurality of image pixels, the monochrome screen comprising a plurality of display pixels, the method comprising the following steps:

- distributing the image pixels into a plurality of groups of pixels;

- successively transmit the groups of pixels from the digital image source to the monochrome screen via the transmission interface, the image pixels of each group of pixels being transmitted in parallel via the transmission channels;

- assign each image pixel received by the monochrome screen to a corresponding display pixel so as to reconstruct the digital image on the monochrome screen.

The method according to the invention may also include one or more of the following characteristics, considered individually or in any technically possible combination.

According to one embodiment, the transmission interface comprises three transmission channels, each group of pixels comprising three image pixels.

According to one embodiment, the display pixels of the monochrome screen form a display matrix, the display pixels being arranged so as to form sets of three pixels called “triplets”, each triplet being a sub-matrix of dimensions (1,3) of the display matrix, the triplets forming a secondary matrix of dimensions (M, N), the image pixels being distributed so that each group of pixels is assigned directly to a corresponding triplet.

According to an implementation mode, each group of pixels is identified by an identification number Nb defined by the following equation:

Nb = N. (i - 1) + j where i and j are whole numbers varying from 1 to M and 1 to N respectively, the groups of pixels being transmitted in ascending order of identification numbers.

According to one embodiment, the display pixels having an identical position in each triplet are associated with the same transmission channel.

According to one embodiment, the display pixels of the monochrome screen form a display matrix, the display pixels being arranged so as to form sets of four pixels called “quadruplets”, each quadruplet being a square sub-matrix of dimension 2 of the display matrix, the quadruplets forming a secondary matrix of dimensions (M ', N'), the image pixels being distributed so as to form repeating patterns each comprising four groups pixels, the image pixels of each repeating pattern being assigned to the display pixels of three consecutive quadruplets belonging to the same row of the secondary matrix.

According to an implementation mode, each repeating pattern is identified by an identification number Nb ’defined by the following equation:

Nb '= N'. (K- 1) +1 'where k and I' are whole numbers varying respectively from 1 to M 'and from 1 to N73, the repeating pattern MR (k, l') comprising a first group of pixels GlNb ', a second group of pixels G2Nb', a third group of pixels G3Nb 'and a fourth group of pixels G4Nb' such as:

Gl _Nb , B {PI (2k - 1.21 - 1); PI (2k - 1.21); Pl (2k, 21-1)};

G2 _Nb , B {Pl (2k, 21); PI (2k - 1, 2 (1 + 1) - 1); Pl (2k, 2 (1 + 1) - 1)};

G3 _Nb , B (Pl (2k - 1.2 (1 + 1)); Pl (2k, 2 (1 + 1)); Pl (2k - 1.2 (1 + 2) - 1)};

G4 _Nb , B {Pl (2k, 2 (1 + 2) - 1); Pl (2k - 1.2 (1 + 2)); Pl (2k, 2 (1 + 2))};

WHERE 1 = 31’-2.

According to one embodiment, the repeating patterns are transmitted in ascending order of the identification numbers.

According to one embodiment, three of the four display pixels of each quadruplet are each associated with a transmission channel, the display pixels associated with the same transmission channel having an identical position in each quadruplet.

BRIEF DESCRIPTION OF THE FIGURES

The invention and its various applications will be better understood on reading the description which follows and on examining the figures which accompany it, among which:

- Figure 1 is a functional diagram of an embodiment of the method according to the invention;

- Figure 2 illustrates a first example of implementation of the method according to the invention;

- Figure 3 illustrates a second example of implementation of the method according to the invention.

The figures are presented only as an indication and in no way limit the invention.

For the sake of clarity, identical or similar elements are identified by identical reference signs in all the figures.

DETAILED DESCRIPTION OF MODES FOR IMPLEMENTING THE INVENTION

FIG. 1 shows a method of transmitting 100 of a monochrome digital image, according to an embodiment of the invention. The monochrome digital image comprises image pixels arranged in the form of an image matrix of dimensions (X, Y), that is to say comprising X rows and Y columns, X and Y being strictly whole numbers positive. The monochrome digital image has an XY definition equal to the number of image pixels it contains, that is to say the product of the number X of lines by the number Y of columns of the image matrix. As the digital image is monochrome, each image pixel is coded on a single component corresponding to a level of light intensity.

The monochrome digital image comes from a digital image source such as a computer, digital camera, or media player. The image source is connected to a monochrome screen via a transmission interface comprising several transmission channels. The transmission interface used is an existing interface intended to transmit digital color images. The pixels of a digital color image are coded on several components that define a color space. Conventionally, this color space is defined by three primary colors such as red, green and blue (RGB). Preferably, the transmission interface therefore comprises a first transmission channel CT1, a second transmission channel CT2 and a third transmission channel CT3. In such an interface, when working with digital color images, each transmission channel is dedicated to the transmission of one of the color components. The transmission interface is for example of the VGA ("Video Graphies Array"), DVI ("Digital Visual Interface), HDMI (" High-Definition Multimedia Interface ") or DisplayPort type.

The monochrome screen comprises an electronic circuit comprising a display matrix made up of display pixels and means for addressing the display pixels. Display pixels are hardware elements configured to emit light based on the level of light intensity encoded in the image pixels. The addressing means allow access to the display pixels to supply them with the image pixels received via the transmission channels.

In the context of the invention, the display circuit of the monochrome screen is advantageously similar to that of a color screen in which each display pixel comprises several sub-pixels including at least one sub-pixel for each color component. These sub-pixels are generally produced by means of a light-emitting diode emitting white light above which a color filter is arranged in order to obtain the emission of the desired color. The monochrome screen display circuit can therefore be obtained by removing these color filters. The sub-pixels of the color screen then become full-fledged pixels in the monochrome screen and the means of addressing remain unchanged. An advantage from an existing display circuit is that it is not necessary in this case to develop a specific display circuit to produce the monochrome screen.

In order to simplify the description and facilitate understanding, it is subsequently considered that the image matrix and the display matrix have identical dimensions, that is to say that they both have the same number X of rows and the same number Y of columns. It is obvious that a person skilled in the art will understand that the matrices can have different dimensions, the definition of the digital image possibly being less than that of the monochrome screen, and will then be able to adapt the invention accordingly.

The transmission method 100 comprises a first step 110 during which the pixels of the monochrome digital image are distributed into groups of pixels. This first step 110 consists in preparing the image pixels to be sent to the monochrome screen. Advantageously, the image pixels are divided into a number of groups equal to the number of transmission channels. It is thus possible to transmit as many pixels simultaneously as there are transmission channels, which makes it possible, for the same clock frequency, to maximize the number of pixels transmitted. In this case, the pixel groups each have three image pixels. The first step 110 is carried out at the level of the image source by programming the sending of the pixels appropriately, as described in more detail in the examples of implementation which will follow.

Then, in a second step 120, the groups of pixels are successively transmitted from the source of digital images to the monochrome screen via the transmission interface. The image pixels belonging to the same group of pixels are transmitted in parallel via the different transmission channels.

The transmission method also includes a third step 130 of allocating each image pixel received by the monochrome screen to a corresponding display pixel. In other words, it's about matching the pixels of the digital image to the pixels of the monochrome screen in order to display the digital image. The third step 130 is carried out at the monochrome screen by appropriately controlling the addressing means.

In the context of the invention, the expression “assigning an image pixel to a display pixel” means the operation consisting in supplying the display pixel with coded information relating to the level of light intensity contained in the pixel of the digital image.

Compared to the transmission of a color image, the quantity of monochrome data transmitted thanks to the invention can be multiplied up to a ratio 3 for the same clock frequency. Since the transmission channels are frequency limited, the invention therefore makes it possible to transmit monochrome digital images having definitions higher than those of digital color images which would be transmitted by the same transmission channels. The invention is particularly interesting for applications favoring the definition of images when needed in color.

In this sense, the present invention finds a particularly interesting application in the field of miniature screens, also called "microdisplays" according to English terminology, for which demand tends towards the highest possible definitions.

For example, the transmission of digital color images to a color screen having a definition of 1280x1024 and at a frequency of 60 Hz is carried out at a pixel frequency of 91 MHz according to the VESA standard ("Video Electronics Standards Association" >> in Anglo-Saxon language). At the same frequency, the invention can make it possible to transmit a monochrome image having a definition of 3840x1024.

Another advantage of the invention is the possibility of working at a lower frequency while maintaining the same image definition, which in particular makes it possible to reduce the consumption of electrical energy.

A first example of implementation of the invention will now be described with reference to FIG. 2. In this example of implementation, the display pixels PA of the monochrome screen are arranged so as to form triplets T , that is to say sets of three display pixels PA. In a color version of such a monochrome screen, each display pixel PA of a triplet T would for example be intended to display one of the three color components of a pixel of a digital color image.

The triplets T form a secondary matrix of dimensions (Μ, Ν), M and N being strictly positive whole numbers. Each triplet T can be identified by a row index i and a column index j, i and j being whole numbers respectively between 1 and M (ie [1; M]) and between 1 and N (je [1; NOT]). Each triplet T is for example made up of three consecutive display pixels PA belonging to the same line of the display matrix. In other words, each triplet T is a sub-matrix of dimensions (1,3) of the display matrix. The secondary matrix therefore has the same number of rows as the display matrix (Μ = X) and a number of columns equal to one third of the number of columns in the display matrix (N = Y / 3). For example, each triplet T (i, j) has a first display pixel PA (i, 3j -2), a second display pixel PA (i, 3j - 1) and a third display pixel PA ( i, 3j).

The triplets T have the same number of pixels as the groups of pixels transmitted via the transmission channels. Each group of pixels is therefore advantageously formed so that it can be directly assigned to the corresponding triplet T. Consequently, each group of pixels comprises the three pixels PI of the digital image having the same coordinates as the three display pixels PA of the corresponding triplet T. From a mathematical point of view, the groups of pixels Gnô and the image pixels PI which they contain respect the following relation:

G _Nb B {PI (i, 3d - 2); PI (i, 3d - 1); PI (i, 3j)} where Nb is an identification number of each group G, Nb being defined by the following equation:

Nb = N. (i - 1) + j for j varying from 1 to N and i varying from 1 to M.

The pixel groups Gn6 are preferably transmitted in ascending order of the identification numbers Nb, that is to say by column index j increasing so as to display a complete row, then by row index i increasing.

Advantageously, the display pixels PA having an identical position in each triplet T are associated with the same transmission channel. In other words, all the display pixels PA having the same position in the triplets T receive image pixels PI transmitted by the same transmission channel. Thus, the step 130 of allocating the image pixels is simplified. For example, the first display pixel PA (i, 3j-2), the second display pixel PA (i, 3j -1) and the third display pixel PA (i, 3j) of each triplet T ( i, j) are associated respectively with the first transmission channel CT1, the second transmission channel CT2 and the third transmission channel CT3, as illustrated in FIG. 2.

A second example of implementation of the invention will now be described with reference to FIG. 3. In this example of implementation, the display pixels PA of the monochrome screen are arranged so as to form quadruplets Q , that is, sets of four pixels. In a color version of such a monochrome screen, three of the display pixels PA of a quadruple Q would for example each be intended to display a color component of a pixel of a digital color image. The remaining PA display pixel could be used to display the blue component, which is less bright than the others, a second time, or to emit white light to increase the pixel's brightness.

The quadruplets Q form a secondary matrix of dimensions (Μ ’, Ν’), M ’and N’ being strictly positive integers. Each quadruple Q can be identified by a row index k and a column index I, k and I being whole numbers respectively between 1 and M '(ke [1; M']) and between 1 and N '(1 e [1; N ']). Each quadruple Q is a square sub-matrix of dimension 2 of the display matrix. Therefore, the number of rows in the secondary matrix is equal to half the number of rows that the display matrix (Μ '= X / 2) and the number of columns in the secondary matrix is equal to half the number of columns of the display matrix (Ν '= Y / 2). For example, each quadruple Q (k, 1) has a first display pixel PA (2k - 1,21 - 1), a second display pixel PA (2k-l, 21), a third display pixel PA (2k, 21-1) and a fourth display pixel PA (2k, 21).

A Q quadruplet has one more pixel than a group of pixels transmitted through the transmission channels. A single group of pixels is therefore not sufficient to completely fill a Q quadruplet. On the other hand, three Q quadruplets have a total number of pixels equivalent to that of four groups of pixels. The image pixels PI are therefore advantageously distributed so as to form repeating patterns MR each comprising four groups of pixels, each repeating pattern MR corresponding to three consecutive Q quadruplets belonging to the same row of the secondary matrix. In this case, each MR repetition pattern can be identified by the row index k and a column index I ’which is an integer between 1 and N73 (e [1; N '/ 3]). Each repeating pattern MR (k, l ') therefore comprises a first quadruplet Q (k, 1), a second quadruplet Q (k, 1 + 1) and a third quadruplet Q (k, 1 + 2) where I and I 'are linked by the following relation:

= 31 '-2.

The repeat motif MR (k, l ’) comprises for example a first group GlNb’, a second group G2Nb ’, a third group G3Nb’ and a fourth group G4Nb ’such as:

Gl _Nb , B {PI (2k - 1.21 - 1); PI (2k - 1.21); Pl (2k, 21-1)};

G2 _Nb , B {Pl (2k, 21); PI (2k - 1.2 (1 + 1) - 1); Pl (2k, 2 (1 + 1) - 1)};

G3 _Nb , B {PI (2k - 1.2 (1 + 1)); Pl (2k, 2 (1 + 1)); PI (2k - 1,2 (1 + 2) - 1)};

G4 _Nb , B {Pl (2k, 2 (1 + 2) - 1); PI (2k - 1.2 (1 + 2)); Pl (2k, 2 (1 + 2))};

where Nb 'is an identification number of each MR repeating pattern, Nb' being defined by the following equation:

Nb '= N'. (K- 1) +1 'for I ’varying from 1 to N73 and k varying from 1 to M’.

The four groups of pixels forming the repeat pattern MR are preferably transmitted in order, that is to say from the first to the fourth. Likewise, the MR repeating patterns are preferably transmitted in order of increasing number Nb ’so as to display the lines of the image two by two. It should be noted that in this example of implementation, the monochrome screen is advantageously equipped with a line memory making it possible to store the image pixels PI received until the complete transmission of two consecutive lines of the image digital.

Advantageously, three of the four display pixels PA of each quadruple Q are each associated with a transmission channel CT1, CT2, CT3, the display pixels PA associated with the same transmission channel CT1, CT2, CT3 having an identical position in each quadruple Q. In other words, three of the four display pixels PA of each quadruplet Q receive image pixels PI transmitted by their respective transmission channel, which is always the same. Thus, the pixel allocation step of the digital image is simplified. On the other hand, the remaining display pixel PA receives a pixel of image PI via a transmission channel which varies according to the coordinates of the quadruple Q.

For example, the first display pixel PA (2k - 1.21 - 1), the second display pixel PA (2k - 1.21) and the third display pixel PA (2k, 21 - 1) of each quadruple Q (k, 1) are respectively associated with the first transmission channel CT1, the second transmission channel CT2 and the third transmission channel CT3. In this case, it is the fourth display pixel PA (2k, 21) which receives its image pixel PI via a variable transmission channel, as illustrated in FIG. 3.

In this exemplary implementation, each group of pixels comprises at most a single image pixel PI (2k, 21) which is assigned to a fourth display pixel PA (2k, 21) of a quadruplet Q (k , 1). Consequently, the variable transmission channel corresponds to that which is not used to transmit the two other PI image pixels of the same group of pixels.

Naturally, the invention is not limited to the embodiments described with reference to the figures and variants could be envisaged without departing from the scope of the invention.

Claims (9)

claims 1. Method for transmitting (100) a monochrome digital image from a source of digital images connected to a monochrome screen by means of a transmission interface comprising a plurality of transmission channels (CT1, CT2, CT3) , the monochrome image comprising a plurality of image pixels (PI), the monochrome screen comprising a plurality of display pixels (PA), the method (100) being characterized in that it comprises the following steps: - (110) distributing the image pixels (PI) into a plurality of groups of pixels (Gnô, G1 Nb ', G2 _Nb ', G3Nb ', G4 _Nb '); - (120) successively transmit the groups of pixels from the source of digital images to the monochrome screen via the transmission interface, the image pixels (PI) of each group of pixels being transmitted in parallel via the channels of transmission (CT 1, CT2, CT3); - (130) assign each image pixel (PI) received by the monochrome screen to a corresponding display pixel (PA) so as to reconstruct the digital image on the monochrome screen. 2. The transmission method (100) according to claim 1, in which the transmission interface comprises three transmission channels (CT1, CT2, CT3), each group of pixels (GNb, G1 Nb ', G2Nb', G3Nb ', G4Nb) with three image pixels (PI). 3. Transmission method (100) according to any one of claims 1 and 2, wherein the display pixels (PA) of the monochrome screen form a display matrix, the display pixels (PA) being arranged to form sets of three pixels called "triplets" (T), each triplet (T) being a sub-matrix of dimensions (1,3) of the display matrix, the triplets (T) forming a matrix secondary of dimensions (M, N), the image pixels (PI) being distributed so that each group of pixels (Gn © is assigned directly to a corresponding triplet (T). 4. Transmission method (100) according to claim 3, in which each group of pixels (GNb) is identified by an identification number Nb defined by the following equation: Nb = N. (ί - 1) + j where i and j are whole numbers varying from 1 to M and 1 to N respectively, the groups of pixels (Gnu) being transmitted in ascending order of the identification numbers. 5. Transmission method (100) according to any one of claims 3 and 4, in which the display pixels (PA) having an identical position in each triplet (T) are associated with the same transmission channel (CT1, CT2, CT3). 6. A transmission method (100) according to claim 1, in which the display pixels (PA) of the monochrome screen form a display matrix, the display pixels (PA) being arranged to form sets of four pixels called "quadruplets" (Q), each quadruplet (Q) being a square sub-matrix of dimension 2 of the display matrix, the quadruplets (Q) forming a secondary matrix of dimensions (M ', N'), the image pixels (PI) being distributed so as to form repeating patterns (MR) each comprising four groups of pixels (GlNb ', G2Nb', G3Nb ', G4Nb), the pixels image (PI) of each repeating pattern (MR) being assigned to the display pixels (PA) of three consecutive quadruplets (Q) belonging to the same row of the secondary matrix. 7. Transmission method (100) according to claim 6, in which each repeating pattern (MR) is identified by an identification number Nb ’defined by the following equation: Nb '= N'. (K- 1) +1 'where k and Γ are whole numbers varying respectively from 1 to M' and from 1 to N73, the repeating pattern MR (k, l ') comprising a first group of pixels GlNb ', a second group of pixels G2Nb', a third group of pixels G3Nb 'and a fourth group of pixels G4Nb' such that: Gl _Nb , B {PI (2k - 1.21 - 1); PI (2k - 1.21); Pl (2k, 21-1)}; G2 _Nb , B {Pl (2k, 21); PI (2k - 1, 2 (1 + 1) - 1); Pl (2k, 2 (1 + 1) - 1)}; G3 _Nb , B {PI (2k - 1.2 (1 + 1)); Pl (2k, 2 (1 + 1)); PI (2k - 1.2 (1 + 2) - 1)}; G4 _Nb , B {PI (2k, 2 (1 + 2) - 1); Pl (2k - 1.2 (1 + 2)); Pl (2k, 2 (1 + 2))}; WHERE 1 = 31’-2. 8. Transmission method (100) according to claim 7, in which the repeating patterns (MR) are transmitted in ascending order of the identification numbers. 5 9. Transmission method (100) according to any one of claims 6 to 8, in which three of the four display pixels (PA) of each quadruplet (Q) are each associated with a transmission channel (CT1, CT2, CT3), the display pixels (PA) associated with the same transmission channel (CT1, CT2, CT3) having an identical position in each quadruplet (Q).